1. Field of the Invention
The present invention relates to an exterior component disposed on a front surface of a radar device of a vehicle and in an electromagnetic wave transmitting and receiving path in front of the radar device mounted on the vehicle.
2. Description of the Related Art
The front grill of an automobile, which is made of resin, usually has a chromium-plated surface which enhances the design's metallic appearance. When a radar device mounted in the rear section of the front grill is used for detecting an obstacle, such as, for example, a vehicle located in front of or ahead of the subject vehicle, an electromagnetic wave transmitted and received by the radar device is reflected from a chromium-plated layer on a front section of the front grill, resulting in a problem wherein the radar device cannot function properly. In order to solve this problem, Japanese Patent Application Laid-open No. 2000-159039 discloses an exterior vehicle component in which a portion of the chromium-plated layer corresponding to an irradiation range of an electromagnetic wave is replaced by an indium-deposited layer by which the electromagnetic wave is transmissible.
An element designed to reflect an electromagnetic wave cannot be disposed in the irradiation range of an electromagnetic wave transmitted from a radar device. Even if the element designed to reflect an electromagnetic wave is present in a region near or proximate to a region outside of the irradiation range, there is a problem that an electromagnetic wave reflected from such an element is superposed on a wave reflected from an object to be detected, such as a vehicle in front of the subject, resulting in a degradation in the detection performance of the radar device.
In this case, the problem is solved by replacing the chromium-plated layer in the area near the region outside of the irradiation range with an indium-deposited layer. However, depositing indium is very expensive compared with chromium plating. Thus, it is desirable to use an inexpensive methodology, such as chromium plating, to coat a layer of the grill and avoid using a more expensive alternative like deposited indium.